Avon Fissure Fill Explained

Avon Fissure Fill
Underlies:Lower Carboniferous limestones
Period:Late Triassic
Age:Norian-Hettangian,
Type:Formation
Extent:Avon (now Bristol)
Namedfor:Avon county
Region:South West England
Coordinates:51.5°N -2.6°W
Paleocoordinates:35.9°N 0.8°W
Year Ts:1836
Namedby:Henry Riley & Samuel Stutchbury

The Avon Fissure Fill, also known as the Bristol Fissure Fill or Tytherington Fissure Fill, is a fissure fill in Avon, England (now Bristol) which dates variously from the Norian and Rhaetian stages of the Late Triassic, or possibly as late as the Hettangian stage of the Early Jurassic.[1] The fissure fill at Avon was a sinkhole formed by the dissolution of Lower Carboniferous limestones.

It is paired with the nearby Magnesian Conglomerate; it may have been the same formation as the Magnesian Conglomerate.[2]

Paleofauna

!Taxon!Species!Presence!Notes!Images
Agnosphitys[3] A. cromhallensisGeographically present in Avon, England (now Bristol).Its remains include a left ilium (holotype) and a left maxilla, astragalus and humerus (referred specimen).
AgrosaurusA. macgillivrayi[4] Geographically present in Avon, England (now Bristol). Originally believed to have been found in Cape York Peninsula, Queensland (Australia).A tibia, a claw and some other fragments.
AsylosaurusA. yalensisGeographically present in Avon, England (now Bristol).[5] Dorsal vertebrae, ribs, gastralia, a shoulder girdle, humeri, a partial forearm, and a hand; additional bones from the neck, tail, pelvis, arm and legs that may represent the same individual.
ChimaeriformesIndeterminateGeographically present in Bristol.Indeterminate remains.
Clevosaurus[6] C. hudsoniGeographically present in Gloucestershire.Partial cranial and post-cranial skeleton (holotype).
CrinoideaIndeterminateGeographically present in Bristol.Reworked from older Carboniferous sediments (Friars Point Limestone Formation).[7]
DiphydontosaurusD. avonensisGeographically present in Bristol.Complete to near-complete specimens.
Hybodontiformes?IndeterminateGeographically present in Bristol.Indeterminate remains.
Gyrolepis[8] IndeterminateGeographically present in Bristol.Indeterminate remains.
LissodusL. minimusGeographically present in Bristol.Teeth.
Palaeosaurus[9] P. cylindrodonGeographically present in Avon, England (now Bristol) and Bristol. Two teeth (one destroyed in 1940).
Planocephalosaurus[10] [11] P. robinsonaeGeographically present in Bristol.Skull (holotype).
RhomphaiodonR. minorGeographically present in Bristol.Teeth.
Rileyasuchus[12] R. bristolensis[13] Geographically present in Bristol.Two vertebrae and a humerus.
Terrestrisuchus?[14] IndeterminateGeographically present in Bristol and South Wales.Indeterminate remains.
TheropodaIndeterminateGeographically present in Avon, England (now Bristol) and Bristol. Indeterminate remains. Possibly similar to Pendraig milnerae.[15]
ThecodontosaurusT. antiquusGeographically present in Avon, England (now Bristol) and Bristol.Partial cranial and postcranial remains (holotype is a lower jaw).

Notes and References

  1. Langer, 2004. Basal Saurischia. In Weishampel, Dodson and Osmolska. The Dinosauria Second Edition. University of California Press. 861 pp.
  2. https://paleobiodb.org/classic/displayStrata?geological_group=&formation=Magnesian%20Conglomerate&group_formation_member=Magnesian%20Conglomerate Magnesian Conglomerate
  3. Nicholas C. Fraser, Kevin Padian, Gordon M. Walkden and A. L. M. Davis, 2002. Basal dinosauriform remains from Britain and the diagnosis of the Dinosauria. Palaeontology. 45(1), 79-95.
  4. H. G. Seeley. (1891). On Agrosaurus macgillivrayi (Seeley), a saurischian reptile from the N.E. coast of Australia. Quarterly Journal of the Geological Society of London 47:164-165
  5. Riley H and Stutchbury S (1836a) "A description of various remains of three distinct saurian animals discovered in the autumn of 1834, in the Magnesian Conglomerate on Durdham Down, near Bristol". Geological Society of London, Proceedings, 2 (45): 397-399.
  6. W. E. Swinton. (1939). A new Triassic rhynchocephalian from Gloucestershire. ''Annals and Magazine of Natural History: Zoology, Botany, and Geology'' '''4''':591-59
  7. Keeble. Emily. Whitestide. David I.. Benton. Michael J.. 2018. The terrestrial fauna of the Late Triassic Pant-y-ffynnon Quarry fissures, South Wales, UK and a new species of Clevosaurus (Lepidosauria: Rhynchocephalia). Proceedings of the Geologists' Association. 129. 2. 99–119. 10.1016/j.pgeola.2017.11.001. 2018PrGA..129...99K . 1983/5afdc677-3ea0-4519-813d-6052ef8370ec.
  8. Romano . Carlo . Koot . Martha B. . Kogan . Ilja . Brayard . Arnaud . Minikh . Alla V. . Brinkmann . Winand . Bucher . Hugo . Kriwet . Jürgen . Permian-Triassic Osteichthyes (bony fishes): diversity dynamics and body size evolution . Biological Reviews . February 2016 . 91 . 1 . 106–147 . 10.1111/brv.12161 . 25431138 . 5332637 .
  9. [Peter Malcolm Galton|Galton, Peter]
  10. Fraser. N.C.. A New Rhynchocephalian from the British Upper Trias. Palaeontology. November 1982. 25. 4. 709–725.
  11. Fraser. N.C.. Walkden. G.M.. The postcranial skeleton of the Upper Triassic sphenodontid Planocephalosaurus robinsonae . Palaeontology. August 1984. 27. 3. 575–595.
  12. [Friedrich von Huene|von Huene, F.]
  13. [Oskar Kuhn|Kuhn, O.]
  14. Mussini . G. . Whiteside . D. I. . Hildebrandt . C. . Benton . M. J. . 2020 . Anatomy of a Late Triassic Bristol fissure: Tytherington fissure 2 . . 131 . 1 . 73–93 . 10.1016/j.pgeola.2019.12.001. 2020PrGA..131...73M .
  15. Spiekman SN, Ezcurra MD, Butler RJ, Fraser NC, Maidment SC . 2021 . Pendraig milnerae, a new small-sized coelophysoid theropod from the Late Triassic of Wales . Royal Society Open Science . 8 . 10 . Article ID 210915 . 10.1098/rsos.210915 . free . 34754500 . 8493203 . 2021RSOS....810915S .

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